2001 Volume 15 Issue 4 Pages 423-431
As one of the conveying methods for solid particles, there is a pneumatic conveyance using pipelines. In such a gas-solid two-phase flow in pipelines in the pneumatic conveyance, it is desirable to tranport particles with a fluid velocity as low as possible from the standpoint of saving energy for transportation, and preventing attrition of particles and abrasion of pipelines. However, in such operations, it is apt to stop eventually its movement due to the deposition of particles on the bottom wall of the pipe. As a result of this, it accompanies with a risk that its transportation becomes impossible. For this reason, it is far more important to study a limiting fluid velocity allowing steady state transport of particles, called the minimum transport velocity, than the investigation on its pressure drop. From such viewpoint in this paper an empirical equation to obtain the minimum velocity for coarse particles in fully developed flow region of a horizontal pipe for low pressure conveying type has been derived based on both model equation and actual transport experiment. In this experiment the particles conveyed is polyethylene pellets. The pipe diameters is 50mm and the pipe distance is about 10.0m. The above mentioned equation can arrange the data in this experiment with a considerably good accuracy, and Molerus’ equation agrees well with the present data.